I've been re-watching the first season of Blake's 7 and I got the idea of drawing up a prisoner transport ship. Here's my work in progress for the prisoner level of the ship. I still have to add some more details here & there but this should give you an idea of how it is going to look. The next level will be the ship command and crew area, hyperspace drive, a couple defensive weapons, etc.

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I picture the cells to have an energy barrier as a door. Each cell has a small area where food (or food tablets) are dispensed and a small area for waste removal. The cells are otherwise spartan in nature. The solitary block has no food dispenser and has only a drain in the floor for waste removal. The cells hold 1 prisoner each with each cell block holding 25 prisoners for a total payload of 50 prisoners. The purpose of this ship is to transport prisoners to penal colonies/stations/what-have-you. This ship could also be used as a slaver ship.